1. From the Texas Heart Institute at St. Luke’s Episcopal Hospital (E.C.P., G.V.S., W.K.V., R.V.C.B., J.T.W.), Houston, Tex; Hospital Procardiaco (H.F.R.D., S.A.S., A.L.S.S., C.T.M., L.B., F.O.D.R., J.A.R.A., H.J.F.D.), Rio de Janeiro, Brazil; Federal University (R.B., A.C.C., M.I.D.R.), Rio de Janeiro, Brazil.